Add "cpack", a library for extracting 1-, 2-, 4-, and 8-octet words

from a buffer.  The cpack library expects for words to appear on
their natural boundaries.

The radiotap (802.11 + radio information) capture format uses cpack
to extract the radio information fields.

diff --git a/cpack.c b/cpack.c
new file mode 100644 (file)
index 0000000..d2e765d
--- /dev/null
+++ b/cpack.c
@@ -0,0 +1,143 @@
+/*-
+ * Copyright (c) 2003, 2004 David Young.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of David Young may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL DAVID
+ * YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+#include <tcpdump-stdinc.h>
+
+#include "cpack.h"
+#include "extract.h"
+
+static u_int8_t *
+cpack_next_boundary(u_int8_t *buf, u_int8_t *p, size_t alignment)
+{
+       size_t misalignment = (size_t)(p - buf) % alignment;
+
+       if (misalignment == 0)
+               return p;
+
+       return p + (alignment - misalignment);
+}
+
+/* Advance to the next wordsize boundary. Return NULL if fewer than
+ * wordsize bytes remain in the buffer after the boundary.  Otherwise,
+ * return a pointer to the boundary.
+ */
+static u_int8_t *
+cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize)
+{
+       u_int8_t *next;
+
+       /* Ensure alignment. */
+       next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize);
+
+       /* Too little space for wordsize bytes? */
+       if (next - cs->c_buf + wordsize > cs->c_len)
+               return NULL;
+
+       return next;
+}
+
+int
+cpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen)
+{
+       memset(cs, 0, sizeof(*cs));
+
+       cs->c_buf = buf;
+       cs->c_len = buflen;
+       cs->c_next = cs->c_buf;
+
+       return 0;
+}
+
+/* Unpack a 64-bit unsigned integer. */
+int
+cpack_uint64(struct cpack_state *cs, u_int64_t *u)
+{
+       u_int8_t *next;
+
+       if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
+               return -1;
+
+       *u = EXTRACT_LE_64BITS(next);
+
+       /* Move pointer past the u_int64_t. */
+       cs->c_next = next + sizeof(*u);
+       return 0;
+}
+
+/* Unpack a 32-bit unsigned integer. */
+int
+cpack_uint32(struct cpack_state *cs, u_int32_t *u)
+{
+       u_int8_t *next;
+
+       if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
+               return -1;
+
+       *u = EXTRACT_LE_32BITS(next);
+
+       /* Move pointer past the u_int32_t. */
+       cs->c_next = next + sizeof(*u);
+       return 0;
+}
+
+/* Unpack a 16-bit unsigned integer. */
+int
+cpack_uint16(struct cpack_state *cs, u_int16_t *u)
+{
+       u_int8_t *next;
+
+       if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL)
+               return -1;
+
+       *u = EXTRACT_LE_16BITS(next);
+
+       /* Move pointer past the u_int16_t. */
+       cs->c_next = next + sizeof(*u);
+       return 0;
+}
+
+/* Unpack an 8-bit unsigned integer. */
+int
+cpack_uint8(struct cpack_state *cs, u_int8_t *u)
+{
+       /* No space left? */
+       if (cs->c_next - cs->c_buf >= cs->c_len)
+               return -1;
+
+       *u = *cs->c_next;
+
+       /* Move pointer past the u_int8_t. */
+       cs->c_next++;
+       return 0;
+}

diff --git a/cpack.h b/cpack.h
new file mode 100644 (file)
index 0000000..14ed376
--- /dev/null
+++ b/cpack.h
@@ -0,0 +1,51 @@
+/*-
+ * Copyright (c) 2003, 2004 David Young.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of David Young may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL DAVID
+ * YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ */
+
+#ifndef _CPACK_H
+#define _CPACK_H
+
+struct cpack_state {
+       u_int8_t                                        *c_buf;
+       u_int8_t                                        *c_next;
+       size_t                                           c_len;
+};
+
+int cpack_init(struct cpack_state *, u_int8_t *, size_t);
+
+int cpack_uint8(struct cpack_state *, u_int8_t *);
+int cpack_uint16(struct cpack_state *, u_int16_t *);
+int cpack_uint32(struct cpack_state *, u_int32_t *);
+int cpack_uint64(struct cpack_state *, u_int64_t *);
+
+#define cpack_int8(__s, __p)   cpack_uint8((__s),  (u_int8_t*)(__p))
+#define cpack_int16(__s, __p)  cpack_uint16((__s), (u_int16_t*)(__p))
+#define cpack_int32(__s, __p)  cpack_uint32((__s), (u_int32_t*)(__p))
+#define cpack_int64(__s, __p)  cpack_uint64((__s), (u_int64_t*)(__p))
+
+#endif /* _CPACK_H */